1. Field of the Invention
The present invention relates to a round baler for forming round bales of harvest products such as hay, straw or wilted grass and including a weighing device for determining the weight of compressed bales.
2. Description of the Prior Act
A round baler with a weighing device is disclosed in U.S. Pat. No. 4,362,097. In the round baler disclosed in U.S. Pat. No. 4,362,097, a rocker is pivotally attached to a side of a round baler by a hydraulic cylinder. A manometer for measuring the pressure is mounted on the hydraulic cylinder. The hydraulic pressure serves as a measure of a bale weight of a bale formed in the baler. With an increase of the bale weight, the compression chamber housing sinks relative to the support axle, the piston moves in the hydraulic cylinder in, increasing the hydraulic pressure. The drawback of this arrangement consists in that the weighing device is mounted only on one side of the baler which lead to imprecise weighing results. Further, no means is provided for correcting false weighing results caused by transverse and/or longitudinal tilt of the baler. Still further, the mounting of the weighing device and its calibration in the mounted conditions is connected with large expenses. Moreover, the measurement results, in particular, at relatively small weights, e.g., about 350 kg/bale for straw, are imprecise because the weighing device also measure the empty weight of the baler which exceeds the bale weight in several time. Also, the running gear forces act as disturbance variables influencing the weighing results.
In an article xe2x80x9cAnsaatze zur automatisierten Arbeitszeitermittlung bei Feldarbeiten (Attachments for Automatic Operational Time Determinationxe2x80x9d, 51, LANDTECHNIK (Agricultural Technology), 4/96, pp. 198-199, there is disclosed a method of determining yield by weighing with the aid of deformation measuring tapes provided on or by measuring the vertical acceleration of the drawbar/axle of the round baler. The described method has the same drawbacks as the weighing method disclosed in U.S. Pat. No. 4,362,097.
German Publication DE 195 43 343 A1 describes a problem encountered during the weight determination of a bale which consists in that the bale, upon being ejected, is in a movable condition, and that the disturbance variables, resulting from the movement of the bale, can prevent a correct weight measurement. To solve this problem, the German reference proposes to stop the movement of a bale for a short time period to weight it, and to provide suitable sensors for determining the disturbance variables and for filtering them out and, also, to effect several measurement one after another to obtain a mean measurement value. A short-time stoppage of the bales adversely affect the thruput of the baler and, at a relatively high bale weight up to 1500 kg/bale of a wilted product, is constructively difficult. This method further requires use of expensive and controllable constructional parts.
Accordingly, an object of the present invention is to provide a weighing device for round balers that would insure a high precision (with a measurement tolerance of less than 2%) of the weight measurement.
Another object of the present invention is to provide a weighing device for round balers that can easily be mounted on conventional round balers without any calibration expenses.
A further object of the present invention is to provide a weighing device for a round baler that would eliminate the influence of the running gear forces and would not include movable elements.
These and other objects of the present invention, which will become apparent hereinafter, are achieved by forming the weighing device as bale unrolling device. The unrolling device is characterized by a simplicity of construction and is suitable for precise weighing of bales.
Usually, round bales are provided with unrolling devices having an inclined plane and which provide for rolling off the bales in an idle condition of the baler after pivotal movement of the rear housing into its open position. The present invention is based on using the rolling movement of the bale for its weighing which provide different advantages such as:
the determination of the bale weight is effected independently from running gear forces and compression forces and independently from the delivery of product and of whether an end of the unrolling device is supported on the ground;
the operation of the baler is not hindered or delayed;
the weighing device is completely integrated in the unrolling device, can be easily mounted and, in particular, can be calibrated before being mounted on a baler;
no modification of the baler itself is necessary;
the weighing device has no movable parts;
the adverse effect of the transverse and longitudinal tilt of the baler can be easily eliminated by correction measures;
the weight tolerances are less than 2%.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.